1. Field of the Invention
The present invention relates to an optical pickup that, is used in a disc device (for example, a DVD recorder, a DVD player, or the like), and more particularly, a disc device capable of preventing a read error by maintaining three-dimensional adjustment and rotation adjustment of a photo detector over a long period.
2. Description of the Related Art
An overview of an optical pickup will be described with reference to FIG. 4. In the optical pickup, a slide base 2 is engaged with, a pair of left and right guide rails 1 disposed along the radial direction pf a disc D to be able to reciprocate. In addition, between surface and bottom sides of the slide base 2, a main substrate 3 formed of a printed circuit board is fixed to one side, and a standing frame 2A is integrally formed or the other side. In the standing frame 2A, a photo detector PD1, a light intensity detector PD2, and a laser diode LD are positioned to be fixed. In addition, within the standing frame 2A, a standing mirror M and a half mirror HM are disposed, and an actuator 4 having an objective lens OL is disposed on one side of the slide base 2.
Hereinafter, the sequence of reading information will be described. The disc D is rotated at high speed and the actuator 4 is driven such that the objective lens OL is moved in a focus direction along a spindle 4a disposed in the actuator 4 and the objective lens OL is moved in the tracking direction around the spindle 4a. Then, a laser beam a emitted from the laser diode LD is reflected by the half mirror HM and the standing mirror M, and is transmitted through the objective lens OL to be projected onto the disc D. Then, reflection light b is transmitted through the objective lens OL, reflected by the standing mirror M, transmitted through the half mirror HM, and received by the photo detector PD1, so that information recorded in the disc D is read out and the intensity of the laser beam a is detected by the light intensity detector PD2.
FIGS. 5 to 8B show an example of a general optical pickup. FIG. 5 is a perspective view of the general optical pickup. FIG. 6 is a plan view of major parts of the general optical pickup. FIG. 7 is a front view of the major parts. FIG. 8A is a development view of a photo, detector conducting wire of the general pickup. FIG. 8B is a view along arrow D-D of FIG. 3A.
As shown in FIG. 5, the laser diode LD is fitted in through a hole, which is formed by perforating a center portion of a holder 6 made of a metal block, to be fixed, and an end portion of a laser diode conducting wire 8 formed of a flexible flat cable that is soldered to a terminal shaft 7 of the laser diode LD is soldered to the main substrate 3.
As shown in FIGS. 5 to 7, the photo detector PD1 is formed by attaching an optical element 11 formed of a photo diode to a support substrate 10 formed of a printed circuit board. The photo detector PD1 is connected to the main substrate 3 through the photo detector conducting wire 12 formed of a flexible flat cable. The structure of the light intensity detector ED2 is the same, as that, of the photo detector PD1. The light intensity detector PD2 is connected to the main substrate 3 through a light intensity detection conducting wire 13 formed of a flexible flat cable.
The sequence of fixing the photo detector PD1 will now be described. The photo detector PD1 is three-dimensionally adjusted in front and rear directions X, in left and right directions Y, and upper and down directions Z with respect to the standing frame 2A, and rotation adjustment T for the photo detector PD1 is performed. Then, by injecting an adhesive agent. 14 such as an ultraviolet curable adhesive agent between the standing frame 2A and the support substrate 10, the photo detector PD1 is fixed to the standing frame 2A.
As shown in FIGS. 8A and 8B, the photo detector conducting wire 12 is formed in an approximate “n” shape by a center portion 12a, one end portion 12b that extends from the center portion 12a at a predetermined tilt angle (in this example, 45°) in one direction, and the other end portion 12c that extends from the center portion 12a at a predetermined tilt angle (in this example, 90°) in another direction. In the inner and outer edges of the end portions 12b and 12c, a plurality of (in this example, seven for each edge) lands 16 is formed, and lands 16 disposed in both the end, portions 12b and 12c are connected together though a plurality of (in this example 14) connect ion wires 17 that pass through the center portion 12a. 
The sequence of connecting the photo detector conducting wire 12 will now be described. As shown in FIGS. 6 and 7, the lands 16 disposed in the one end portion 12b are soldered to lands 18 of the main substrate 3, the other end portion 12c is bent to rise in the boundary K between the center portion 12a and the other end portion 12c, and the lands 16 of the other end portion 12c are spidered to the lands 18 of the support substrate 10, as disclosed in Japanese Patent Publication No, 2000-331372.
In the above-described configuration, the photo detector conducting wire 12 is formed of a flexible flat cable having a large width. Accordingly, when the other end portion 12c thereof, is bent to stand in the boundary K, a strong pulling force P is generated along the outer edge of the photo detector conducting wire 12 from the boundary K, and a strong compressing force F is generated along the inner edge of the photo detector conducting wire 12. Thus the strong pulling force P and the strong compressing force F are applied to the adhesive, agent 14 that supports the photo detector, and the adhesive agent 14 is deformed in a case where the adhesive agent is exposed, in a high-temperature environment such as a curing process or a warehouse. As a result, the three-dimensional, adjustment XYZ and rotation adjustment of the photo detector PD1 may be performed incorrectly, and thereby there is a possibility of generation of a read error.